Printed circuit boards commonly have terminals thereon, of both male and female varieties, for connecting the board circuit with other electronic components, such as potted integrated circuits. It is customary to provide an opening in the printed circuit board where a terminal is to be installed. A pin-like extension of a terminal is inserted into the opening in the circuit board and then soldered to the board.
When a plurality of terminals are to be installed in an array of predetermined configuration, it has been the practice to provide a carrier for the group of terminals, which carrier can support and transport the group in its desired configuration.
U.S. Pat. No. RE 32,540 dated Nov. 10, 1987, to J. V. Murphy for "Terminal Positioning Method and Construction" contains an excellent description of a prior art carrier system in which downwardly extending fingers on an aluminum plate enter the socket portions of an array of female terminals to support and transport the terminals. This patent also alludes to the shortcomings of the aluminum plate carrier system, such as possible damage to delicate terminals, and an inability to carry terminal arrays having more complex configurations than simple single in-line and double in-line positioning of terminals.
The Murphy patent teaches that the shortcomings of the aluminum plate carrier can be overcome by releasable retaining the terminals arranged in the desired configuration in openings provided in a thin, flexible plastic sheet. The sheet is peeled away from the terminals after the latter have been soldered to the circuit board. The problem with this approach is that the flexible sheet does not provide a stable support for the terminals with the result that the terminals can become misaligned during assembly or move during soldering, providing faulty connections.
Another common practice today is to provide rigid, molded plastic carriers for holding the terminals in the desired configuration. These carriers usually remain on the terminals after soldering, thus adding weight and taking up valuable space on the circuit board.
A somewhat different approach to terminal carrier supports is disclosed in U.S. Pat. No. 4,420,877, granted Dec. 20, 1983, to J. A. McKenzie, Jr., for "Self-Masking Socket Pin Carrier For Printed Circuit Boards". McKenzie proposes to injection mold carriers in various configurations of nylon plastic material. In order to be removable after the terminals are soldered to the board, these plastic carriers only loosely hold the terminals, again allowing possible misalignment of the terminals during transport.
U.S. Pat. No. 4,878,851, granted Nov. 7, 1989, to W. B. Mullen III for "Electrical Socket Apparatus With Temporary Housing" is concerned with printed circuit technology, but addresses a different problem. This invention seeks to prevent solder from entering the interior of an electrical socket being installed in a printed circuit board. The inventor accomplishes this objective by encasing the socket in a temporary housing shaped to fit the opening in the circuit board which receives the socket. The housing is fabricated from a soluble material which can be dissolved in a solvent, such as warm water.
Soluble spacer components have also been employed in circuit board manufacture. Bivar, Inc. of Irvine, Calif., produces a line of wash-away component mounting spacers which are sold under the trademark "DISS-O-PADS". These spacers are placed beneath electrical components, such as resistors, condensers, transistors, etc., usually around leads from such components, to space the components from the printed circuit board. The spacers are made from a sugar compound which can be dissolved in water after the components have been soldered to the board.
There continues to be a need for a terminal carrier system which reliably positions and holds terminals in a predetermined configuration during transport, assembly, and soldering and which can easily be removed from the circuit board after the soldering operation is complete.